This invention relates to a roll type conveyor system of transporting articles along a generally linear path of travel and, in particular, to a simple and compact conveyor that is capable of safely providing a number of speed adjusting functions while using a minimum number of moving parts.
Many roll type conveyors are in use today which have the ability of controlling the speed of an article in transit. Although these conveyors for the most part operate quite well, these machines are generally rather heavy and space consuming devices that utilize complex and expensive roller mechanisms. Because of the size and weight involved, special precautions sometimes must be taken to adequately support the equipment in a building or the like which add to the overall expense of the equipment.
In U.S. Pat. No. 3,894,627, a moving roll conveyor is described that has the ability to adjust the speed of the article support rollers and thus the speed of an article situated thereon.
In order to maintain separation between articles, the conveyor rollers are subdivided into individual flights. Each flight contains a number of nonpowered or idler rollers that are interposed between driven or powered rollers. The powered rollers positioned forward of the idlers in the direction of conveyor travel are rotated in a direction so as to move an article situated thereover rearwardly toward the idlers. The powered rollers positioned behind the idlers are turned in the opposite direction so as to push an article situated thereover forward toward the idlers. Accordingly, articles riding on the conveyor tend to assume a center position in each flight thereby establishing a uniformly spaced file of articles traveling along the conveying path.
Although a number of different speeds can be imparted to an article in transit by this prior art device, it should be noted that the speed functions are not selectively programmable. Consequently, one article can very well move out of one flight into an adjacent flight thereby disturbing the spacing of the articles in transit. Similarly, in the event the forward progress of one article is slowed or stopped, the faster moving articles that follow will contact the slower moving articles causing a chain reaction. When delicate articles are being conveyed, this type of chain reaction can cause breakage. It should be noted that all of the rollers in each flight are secured to the drive chain. Each of the rollers thus requires a pair of relatively heavy end caps for engaging the chains. It is also well known in the art that closely spaced, positively driven, rollers of this nature are capable of grabbing and holding the limbs and clothing of persons using the conveyor. Oftentimes bodily harm results before the machinery can be shut down.
U.S. Pat. No. 2,154,844 also discloses a roll type conveyor for transporting test tubes through a number of work stations. The tubes are laid laterally on top of two rows of travelling discs. In operation, pressure is applied to either the discs or the tubes to impart a prescribed rotational motion to the work as it passes through the various work stations. Here again, the apparatus is rather bulky and complex requiring a large number of cooperating parts to achieve the desired results.